Gallium Plasmonic Nanoantennas Unveiling Multiple Kinetics of Hydrogen Sensing, Storage, and Spillover

Abstract

hydrogen sensing and storage new materials solutions are needed to reduce thermodynamic (process-temperatures limitations) and kinetic (process rate limitations) barriers and meet the challenges of sensing of a response time of less than 1 s, an operating temperature of −30 to 80 degrees Celsius, and a measurement of 0.1% to 10%, [1] as well as of hydrogen storage with low hydrogen refilling time and output power.The integration of plasmonics [2] with the recently introduced concept of novel catalytically-active liquid metal hydrides and hydrogen trapping mechanisms represents a breakthrough toward creating a new generation of plasmonic-enhanced photocatalytic nanosystems for enhancing both hydrogen sensing [3] and storage. [4] Surface-plasmon-resonance (SPR) induces electromagnetic field enhancement on common hydrogen-absorbing metals such as magnesium (Mg), palladium (Pd), titanium (Ti), and nickel (Ni) which may be exploitable in the microwave region for hydrogen storage. [5,6] Previous studies have reported SPR hydrogen sensing platforms based on Pd, [7,8] gold (Au), [9][10][11] aluminum (Al), [12] and Mg [13] nanoparticles (NPs). Considering the essential requirements for hydrogen storage, such as high storage capacity and fast hydrogen adsorption kinetics, requirements of hydrogen Hydrogen is the key element to accomplish a carbon-free based economy. Here, the first evidence of plasmonic gallium (Ga) nanoantennas is provided as nanoreactors supported on sapphire (α-Al 2 O 3 ) acting as direct plasmonenhanced photocatalyst for hydrogen sensing, storage, and spillover. The role of plasmon-catalyzed electron transfer between hydrogen and plasmonic Ga nanoparticle in the activation of those processes is highlighted, as opposed to conventional refractive index-change-based sensing. This study reveals that, while temperature selectively operates those various processes, longitudinal (LO-LSPR) and transverse (TO-LSPR) localized surface plasmon resonances of supported Ga nanoparticles open selectivity of localized reaction pathways at specific sites corresponding to the electromagnetic hot-spots. Specifically, the TO-LSPR couples light into the surface dissociative adsorption of hydrogen and formation of hydrides, whereas the LO-LSPR activates heterogeneous reactions at the interface with the support, that is, hydrogen spillover into α-Al 2 O 3 and reverse-oxygen spillover from α-Al 2 O 3. This Ga-based plasmon-catalytic platform expands the application of supported plasmoncatalysis to hydrogen technologies, including reversible fast hydrogen sensing in a timescale of a few seconds with a limit of detection as low as 5 ppm and in a broad temperature range from room-temperature up to 600 °C while remaining stable and reusable over an extended period of time.

Plasmonic Active “Hot Spots”‐Confined Photocatalytic CO2 Reduction with High Selectivity for CH4 Production

“…The tiny gaps (< 10 nm) between plasmonic nanostructures are classical “hot spots” formed due to the plasmon coupling between the inter‐nanostructures. [ 14,34–36 ] These plasmon‐coupled hot spots can serve as high‐power “generators” for increasing the continuous output of localized hot‐electrons ( Figure a). [ 37,38 ] In this context, the intercalation of an appropriate semiconductor into the plasmon‐coupled hot spot would suppress the fast relaxation of the hot electrons through an ultrafast hot‐electron transfer from the plasmonic nanostructures to semiconductor across their hetero‐interface.…”

“…The tiny gaps (< 10 nm) between plas monic nanostructures are classical "hot spots" formed due to the plasmon coupling between the internanostructures. [14,[34][35][36]…”

Computational Design of Alloy Nanostructures for Optical Sensing of Hydrogen

“…After fitting the DFs to a Lorentzian representation (as described in Supplementary Note 1) we carry out FDTD simulations of the optical response of truncated cone nanodisks (Fig. 2a), characterized by their height h (20-40 nm) and aspect ratio (AR) (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12) or diameter d = AR × h on a silica substrate, mimicking nanodisks fabricated by the hole-mask colloidal lithography method [30]. The exact shape of the nanodisk is, however, not of great importance (see Fig.…”

“…As a result, hydrogen sensing continues to be a very active research field with the goal of providing fast, reliable, and longterm stable hydrogen sensors that can prevent major accidents. Several different sensing platforms have been proposed, typically based on the change in optical [2][3][4][5][6][7][8][9][10][11][12] or electrical [13][14][15] properties of a material during hydrogen absorption. Many of these devices are based on palladium (Pd), which forms a hydride phase upon exposure to a hydrogen-rich atmosphere.…”

Computational Design of Alloy Nanostructures for Optical Sensing of Hydrogen

“…As a result, hydrogen sensing continues to be a very active research field with the goal of providing fast, reliable, and long-term stable hydrogen sensors that can prevent major accidents. Several different sensing platforms have been proposed, typically based on the change in optical − or electrical − properties of a material during hydrogen absorption. Many of these devices are based on palladium (Pd), which forms a hydride phase upon exposure to a hydrogen-rich atmosphere.…”